Safety is a very important design aspect of a hand grenade fuze. Fuze designs account for a time delay period from initiation, for the detonation to occur, in order to ensure that the grenade is cast outside the explosion hazard area. As a result, it is essential that this time delay does not run short, and be precisely controlled.
Some of the current hand grenades employ a simple chemical powder delay column to effect a timing delay before function, which is permanently in-line with a primer explosive element and a detonator/high explosive fill, creating a potential safety hazard and the ability for unintended initiation of the device. For example, overheating due to inflammation, or primer functions at low temperatures. In addition, this method of fuzing does not offer a very accurate, repeatable delay time across many units, due to hygroscopic effects on the powder and poorly controlled delay column densities.
Conventional mechanical time delay fuzes are either operated by a spring or a pyrotechnic delay element. However, these mechanical delay fuzes present numerous inherent problems, including but not limited to: the inability to be stored for an extended period of time, inconsistent timing to detonation, dependency on temperature, susceptibility to aging, subject to manufacturing inaccuracy.
Conventional electric time delay mechanisms have been designed to overcome the problems associated with the mechanical time delay mechanisms. These electric time delay mechanisms generally included an electric energy source and an electronic delay circuit. Even though these electric time delay circuits have proven to be more reliable than their mechanical counterparts, they in turn, present inherent disadvantages. As an example, the electric time delay mechanisms are predisposed to unintended electrical activation, that can lead to the premature and unintentional detonation of the hand grenade.
What is therefore needed is a fuze design that overcomes the aforementioned problems associated with the conventional in-line (primer to detonator) mechanical and electrical time delay mechanisms, and yet still fits within the existing hand grenades designs, with minimal manufacturing variances, in order to maintain the same user directions and training as for existing hand grenades. Prior to the advent of the present invention, the need for such a fuze design has heretofore remained unsatisfied. The minimal manufacturing variances are important in order to allow the use of conventional manufacturing, such as molding, machining, etc., and further to minimize changes to the assembly lines.